Pollution in Four Industrialised Estuaries. Studies in Relation to Changes in Population and Industrial Development.

Nitrogen isotopes in herbaria document historical nitrogen sewage pollution in the Mersey Estuary, England

“…55 Between 1847 and 1858 an 80-mile-long sewer network with 48 outows discharging into the River Mersey was constructed, focusing sewage waste in the river. 38,56 Sewage waste in England reached such a level that it caused several national cholera outbreaks; 57 the largest of these outbreaks occurred in 1849. It is interesting to observe that the 1849 cholera outbreak coincides with the most elevated d 15 N value (Bootle, +21.5&) in our herbaria record and Liverpool having the highest cholera mortality rate in large towns reported for England (Liverpool, 11.3 deaths per 1000 people).…”

“…61 Although raw sewage can explain the d 15 N record, agricultural practices cannot be excluded. 38,56 In addition, leaching and weathering of soil-derived nitrogen from elds using organic fertilisers (i.e., manure) may also be contributing to the d 15 N signature. 24 To our knowledge no soil-nitrogen isotope studies exist for Merseyside.…”

“…68 In the 1970s the Mersey Estuary was considered the most polluted estuary in the UK receiving signicant wastewater inputs that subsequently led to high nitrate plumes in Liverpool Bay. 34,38,41,56,64 High nutrient uxes as a result of sewage wastewater discharges caused biochemical oxygen demand (BOD) in the late 1960s to average 20 mg l −1 which is indicative of very polluted water. The enriched d 15 N values observed in herbaria collected for this interval corroborate the input of denitried sewage wastewater (Fig.…”